# Questions tagged [indexed-variable]

Questions about indexed variables and related alternative methods to allow assigning indexed names to objects.

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### Undefined Indexed Variable

I searched already a lot about indexed Variables, and it tends to be the most applicable way to use tensor notation. But I am having a hard time to solve for undefined indexed variables: Here my ...
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Mathematica/Wolfram Language newbie here. The behavior I am after is to be able to "overload" the subscripting of me-defined objects/Heads and thereby use them as if they were ...
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### Referring to matrices with index

For exampe I have two matrices, with index 1 and 2 Mat[1] = ConstantArray[0, {2, 2}] Mat[2] = ConstantArray[0, {2, 2}] I wanna assign new value with ...
120 views

### How to use a list of indexes as a variables inside a Module?

This is a trivial function, just to show that Module does not recognize the list generated by Table. ...
31 views

### How does Mathematica evaluate sums where the upper limit of the index is not an integer?

I am interested in the way Mathematica evaluates sums where the upper limit of the index is not an integer - i.e., sums that are some sense mathematically meaningless. For example: ...
104 views

### Define implicit dummy index?

I've been looking for a solution to this question for a while. I was wondering if anyone is aware of a way of defining symbolic dummy indices to implement Einstein's convention. Let me explain with an ...
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### Subscripts use to make expression readable [duplicate]

I am trying to write a function in mathematica which depends on different parameters. For example $$f(x_1, x_2, x_3, x_4, x_5)= 2x_1+\sin(x_2)+x_3*x_4-x_5^{-1}$$ (My actual function has 12 such ...
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### How to create a nested list of variable depth with indexed elements

i want to obtain this definition of a nested list t = Table[C[i, j], {i, 3}, {j, 3}] with arbitrary depth, ...
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### Parallelize import of many files

I'm trying to speed up the import of a large number of files, using ParallelTable to store them in a indexed variable, eqDump. The files are in the folder "Frames" and are named "Conf_Run.1000", "...
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### Getting a stored variable from its value

Given a numerical value, is it possible to check whether that value is stored in (or defines) some variable in the notebook? Maybe if I could list all of the defined variables, then I could simply ...
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### Create list of values with arbitrary index and the use it in a function

I have the following generating functions: $l_{2i-1}=l_{1}-(i-2)(w+s)$ with $i\geq 2$ and $l_{2i}=l_{2}-(i-1)(w+s)$ with $i\geq 2$, so the first one is for odd index and the second for even index. ...
57 views

### Taking a Part of a Part of a Variable

Say I have Part of a variable x. Part[x, 1] Then, I'll get an error message, as the ...
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### Naming indexed output streams

I need to write into multiple files in a Do loop. Hence, I tried to open multiple streams: ...
45 views

### How to truncate equation with multivariables

I am trying to set certain terms zero. How to set terms with greater than 'a3' and 'an3' zero in the following equation: ...
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### ParallelDo with doubly-indexed iterators

What is the reason that ParallelDo works with singly-indexed iterators, but not doubly- or more-indexed iterators? For example, the code ...
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### Symbolic summation with variable bounds and variable number of indices

I wish to compute compute terms like Sum[f[t[j[1]],t[j[2]],...],{j[1],m},{j[2],n},...] for arbitrary positive integer n and any ...
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### Multivariable functions symmetric in their arguments/representing indexed coefficients

Context: I have equations for indexed coefficients $C_{ij}$ which I have represented using 2-variable functions in Mathematica. e.g., ...
126 views

### subscript index notation select certain value [closed]

I have an indexed variable Subscript[p, s, m, t] established using the Notation method. There are various expressions where s, <...
63 views

### How do we input powers of indexed variables?

I have tried (a[i])^2 and alternatively (a^2)[i] Apparently both seem to work, but I was wondering what was the right way ...
152 views

### How do I get Mathematica to invert a matrix with subscripts involved? (Subscript usage)

I want Mathematica to invert a matrix in which all variables are symbolic including Subscript. Now I am guessing this has something to do with the method I'm ...
573 views

### Combining Multiple Lists

Let's say I have 4 lists: list1 = {a,b,c,d}; list2 = {e,f,g,h}; list3 = {i,j,k,l}; list4 = {m,n,o,p}; I can combine them using Join ...